EVALUATION OF ANTIBIOTIC-RESISTANT BACTERIA IN TERTIARY TREATED WASTEWATER ...

119 Pages·2010·7 MB·English

by  Rachel Rosenberg Goldstein

ABSTRACT

Title of Document: EVALUATION OF ANTIBIOTIC-RESISTANT
BACTERIA IN TERTIARY TREATED
WASTEWATER, RECLAIMED
WASTEWATER USED FOR SPRAY
IRRIGATION, AND RESULTING
OCCUPATIONAL EXPOSURES.

Rachel Elizabeth Rosenberg Goldstein, Master
of Public Health in Environmental Health, 2010

Directed By: Dr. Amy R. Sapkota, Assistant Professor,
Maryland Institute for Applied Environmental
Health

Occupational exposures to vancomycin-resistant Enterococcus (VRE) and
methicillin-resistant Staphylococcus aureus (MRSA) in reclaimed wastewater used for
spray irrigation were evaluated. In 2009, wastewater was collected from a tertiary-
treatment facility, and reclaimed wastewater, nasal and dermal swab samples from an
irrigation site. Samples were evaluated for MRSA and VRE using standard methods,
PCR, and susceptibility testing. MRSA and VRE were isolated from all wastewater
samples except effluent. While wastewater MRSA isolates were multidrug resistant
(98%), no MRSA was isolated in irrigation water or swabs. VRE was isolated in one
irrigation water sample. Fewer irrigation workers were colonized with S. aureus (31%)
compared to controls (46%), but they harbored more multidrug resistant S. aureus. This is
the first study to 1) evaluate antibiotic-resistant bacteria (ARB) in U.S. reclaimed
wastewater and resulting occupational exposures, and 2) detect MRSA in U.S.
wastewater. The findings suggested that tertiary wastewater treatment effectively reduced
MRSA and VRE.
EVALUATION OF ANTIBIOTIC-RESISTANT BACTERIA IN TERTIARY
TREATED WASTEWATER, RECLAIMED WASTEWATER USED FOR SPRAY
IRRIGATION, AND RESULTING OCCUPATIONAL EXPOSURES.

By

Rachel Elizabeth Rosenberg Goldstein

Thesis submitted to the Faculty of the Graduate School of the
University of Maryland, College Park, in partial fulfillment
of the requirements for the degree of
Master of Public Health in
Environmental Health
2010

Advisory Committee:
Dr. Amy R. Sapkota, Chair
Dr. Betty J. Dabney
Dr. Gary Felton
Dr. Sam W. Joseph
Dr. Amir Sapkota
© Copyright by
Rachel Elizabeth Rosenberg Goldstein
2010
Dedication
For my mother, and my friend, Ellen Witte Rosenberg, who told me that I have the
potential to do and be whatever I want.
ii
Acknowledgements
I would like to thank my husband, Paul Goldstein, for his unwavering support and
enthusiasm for my work and everything I do. His love and encouragement have been
essential to my ability to grow and prosper throughout my graduate studies.
My family (Rosenbergs, Wittes, and Goldsteins) has always supported my
education and efforts to improve the environment and public health. Through good times
and bad, I have always been able to count on them. Thank you all.
Dr. Amy R. Sapkota has been my adviser, mentor, and all-around champion. She
has encouraged me to challenge myself and take advantage of opportunities as they arise.
With Dr. Sapkota’s support I have been given the chance to engage myself fully in
science. She has helped me focus on the big picture and stoked my passion for
environmental health. I cannot thank her enough for providing me with these
opportunities and her guidance.
I would like to thank the rest of my thesis committee, Dr. Betty J. Dabney, Dr.
Gary Felton, Dr. Sam W. Joseph, and Dr. Amir Sapkota, for their enthusiasm for my
project and their assistance in strengthening my study and my thesis.
Dr. Shirley Micallef taught me the basics of microbiology lab work, to find
excitement and joy in what you do, and to be proud of your work. Her mentoring and
friendship have been invaluable.
Mr. Ashish George lent his time and hands to this project in the lab. Thank you.
Mr. John Martin and Mr. John Denholm, generously provided their time and
knowledge to this project. My thesis would not have been possible without their
cooperation.
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Table of Contents

Dedication...........................................................................................................................ii

Acknowledgements............................................................................................................iii

List of Tables.....................................................................................................................vi

List of Figures...................................................................................................................vii

Chapter 1: Introduction.......................................................................................................1

Water Use........................................................................................................................1

Microbial Contaminants in Wastewater..........................................................................3

Public Health Risks.........................................................................................................4

Research Rationale..........................................................................................................5

Chapter 2: Background.......................................................................................................6

Introduction.....................................................................................................................6

Staphylococcus aureus....................................................................................................6

Genus Description.......................................................................................................6

Species Description.....................................................................................................7

Ecological Habitat and Distribution............................................................................8

Epidemiology and Pathogenicity..............................................................................10

Methicillin Resistance...............................................................................................11

Enterococcus spp..........................................................................................................13

Genus Description.....................................................................................................13

Ecological habitat and distribution...........................................................................13

Epidemiology and Pathogenicity..............................................................................14

Vancomycin Resistance............................................................................................14

Wastewater Treatment in the United States..................................................................16

Bacteria in wastewater..................................................................................................18

Antibiotic-Resistant Bacteria in Wastewater................................................................19

Aerosolization of Pathogens at Wastewater Treatment Plants.....................................21

Seasonal Variations.......................................................................................................22

Reclaimed Wastewater Use in the United States..........................................................23

Conclusion....................................................................................................................25

Chapter 3: Short form manuscript: Reductions of Methicillin-resistant Staphylococcus
aureus and Vancomycin-resistant Enterococcus spp. at a U.S. Tertiary Wastewater
Treatment Plant.................................................................................................................27

Abstract.........................................................................................................................27

Introduction...................................................................................................................27

Methods.........................................................................................................................28

Results...........................................................................................................................30

MRSA and MSSA....................................................................................................30

VRE and VSE...........................................................................................................30

Antimicrobial Susceptibility.....................................................................................31

Discussion.....................................................................................................................32

Conclusions...................................................................................................................35

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Chapter 4: Antibiotic-Resistant Bacteria Present in Reclaimed Wastewater and
Occupational Exposure at a Spray Irrigation Site.............................................................43

Abstract.........................................................................................................................43

Introduction...................................................................................................................44

Goals.........................................................................................................................45

Methods.........................................................................................................................45

Site Description.........................................................................................................45

Sample Collection.....................................................................................................46

Questionnaire............................................................................................................48

Isolation.....................................................................................................................48

Identification.............................................................................................................51

Results...........................................................................................................................53

Water.........................................................................................................................53

Air.............................................................................................................................53

Nasal and Dermal Swabs..........................................................................................54

Discussion.....................................................................................................................55

Water.........................................................................................................................55

Air.............................................................................................................................59

Nasal and Dermal Swabs..........................................................................................59

Limitations....................................................................................................................61

General......................................................................................................................61

Water.........................................................................................................................62

Nasal and Dermal Swabs..........................................................................................62

Conclusions...................................................................................................................64

Chapter 5: Overall Conclusions and Public Health Implications.....................................70

Summary.......................................................................................................................70

Public Health Implications............................................................................................72

Concluding Thoughts....................................................................................................75

Appendices........................................................................................................................78

A. Reclaimed Wastewater Spray Irrigation Project Protocol...........................................78

B. Participant Questionnaire.............................................................................................94

Bibliography.....................................................................................................................96


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List of Tables

Table 1: MIC distributions for 12 antibiotics observed among
methicillin-resistant Staphylococcus aureus collected from
different sampling locations at a tertiary wastewater treatment
plant 40

Table 2: Percentage of multidrug resistant methicillin-resistant S.
aureus (MRSA) and methicillin-susceptible S. aureus (MSSA)
(fraction of total isolates per season) 41 40

Table 3: MIC distributions observed among methicillin-
susceptible Staphylococcus aureus collected from different
sampling locations at a tertiary wastewater treatment plant 42

Table 4: Minimum inhibitory concentrations (MICs) of select
Staphylococcus aureus and methicillin-resistant coagulase
negative Staphylococcus isolates from spray irrigation and
office workers’ nasal and dermal swabs 68

Table 5: Demographic characteristics and risk factors of spray
irrigation workers and office worker controls 69

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List of Figures

Figure 1: Typical wastewater treatment plant process steps 26

Figure 2: Colony forming units (CFU) per milliliter (CFU/mL) of
vancomycin-susceptible Enterococcus spp. found in selected
wastewater samples 37

Figure 3: Colony forming units (CFU) per milliliter (CFU/mL) of
vancomycin-resistant Enterococcus spp. found in selected
wastewater samples 38

Figure 4: Average number of antibiotics that MRSA isolates
display resistance to in different treatment steps of a tertiary
wastewater treatment facility in the Mid-Atlantic Region (n = total
number of isolates in sample type from both collection dates) 39

Figure 5: Spray irrigation site: reclaimed wastewater treatment and
distribution process 65

Figure 6: Concentration of Enterococcus spp. and vancomycin-
resistant Enterococcus spp. in reclaimed wastewater used for spray
irrigation samples 66

Figure 7: Percentage of methicillin-susceptible Staphylococcus
aureus nasal swab isolates from spray irrigation worker and office
worker controls expressing resistance to common gram-positive
antibiotics 67

Figure 8: Number of Treatment Facilities and Population Served
per State by Level of Treatment for Year 2004 76
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